1. Field of the Invention
Embodiments of the present invention relate to techniques for routing data in a network. More specifically, embodiments of the present invention relate to a method for performing load balancing using multiple paths at a node.
2. Related Art
The ever-growing Internet traffic, combined with numerous emerging wireless applications, is placing a progressively heavier burden on network links. Load balancing is an important technique for mitigating network congestion and for removing “hot-spot” links in a network. With load balancing, a node forwards a received data packet to different output links, and hence onto multiple paths leading to the same destination.
A number of approaches are currently available for establishing multiple paths from a source to a destination by finding “link-disjoint” or “node-disjoint” paths. Finding link- or node-disjoint paths, however, introduces additional states into the network, and hence makes path maintenance much more complicated. As a result, maintaining the network states to preserve disjoint paths can be very expensive. The use of link-disjoint or node-disjoint paths is largely motivated by the concern for network reliability, because a link-disjoint or node-disjoint path can eliminate a single point of failure, such as a node failure or a link failure. However, using only link-disjoint or node-disjoint paths imposes unnecessary constraints to load balancing, because load balancing can only occur at the source node or at a node which intersects multiple paths.
Moreover, imposing link or node disjointedness is particularly burdensome to a heterogeneous network, such as a mobile ad hoc network for wireless devices. Wireless devices often have multiple network interfaces based on different technologies and protocols. For example, a given wireless device can have interfaces for IEEE 802.11 WiFi technology, Bluetooth technology, 2G or 3G cellular data-interface technology, and IEEE 802.15.4 Zigbee technology, and infrared technology. In such a heterogeneous network, imposing link-disjointedness or node-disjointedness can prevent the user from utilizing otherwise usable links.
Furthermore, in a heterogeneous network, a link may have multiple metrics, such as hop count, physical distance, bandwidth, queuing delay, and communication cost. A load-balancing scheme based on consideration of only one metric cannot efficiently achieve an optimal result.
Hence, there is a need for a method and an apparatus for performing multi-path load balancing which accommodates multiple link metrics without imposing link or node disjointedness.